Storage Evaluation Of Fulvic Acid Bio-organic Fertilizer And Its Effects On Soil Bacteria And Physical And Chemical Properties

In recent years,Fulvic acid bio-organic fertilizer has become a hot new type of fertilizer in the fertilizer industry.It has a good performance in application.However,the short shelf-life of Fulvic acid bio-organic fertilizer is a key problem for the healthy development of the industry,and its impact on the release of soil nutrients and soil microbial community structure is less studied.Through the self-made fulvic acid bio-organic fertilizer(FMO)and the simulated fertilizer preservation test,the changes of p H,effective viable bacteria number and nutrients of fulvic acid bio-organic fertilizer during the shelf life were discussed,which provided the basis for prolonging the shelf life,the effects of fertilizer application on soil physical and chemical properties and bacterial community structure were studied through soil fertilization experiment,which provided theoretical basis for the application of fulvic acid bio-organic fertilizer.The main findings are as follows.The structure of Fulvic acid bio-organic fertilizer was observed by SEM.The structure of Fulvic acid was spherical and porous.Bacterial powder can be adsorbed on the pores and surface of Fulvic acid.After Fulvic acid bio-organic fertilizer is made,the microbial mycelium is dispersed and adsorbed on the surface and the crevices of the saprophyte.The results of simulated preservation test showed that the number of effective viable bacteria of FMO stored at 20°C,28°C and 35°C decreased during shelf life,and the number of effective viable bacteria of FMO stored at 20°C was significantly different after about 135 days(P<0.05),when stored at higher temperatures,this time is shortened to about 105 days at 28°C and to about 45 days at 35°C.The number of effective viable bacteria of FMO stored at 35°C decreased the most in shelf-life,which was 44.6%.The p H of FMO kept at 35°C had a significant effect on the number of effective viable bacteria,the contents of Fulvic acid(FA)and organic matter(OM)in FMO stored at 35°C changed rapidly according to the changes of nutrients measured(P<0.05),the production rate of FA content will be lower than consumption in about 120 days,and the total FA content in FMO will decrease.Total nitrogen(TN)and total phosphorus(TP)in FMO stored at 35°C decreased significantly(P<0.05)in about 120 days,while total potassium(TK)remained stable in shelf life.The nutrient and the number of effective viable bacteria of FMO stored at constant temperature under the designed temperature met the industry standard during the shelf life.In summary,the best storage time of FMO at 20°C was within 135 days,at 28°C was within 105 days,and at 35°C was within45 days.The results of soil fertilization experiment showed that 15°C and 20°C could significantly increase the biomass of soil effective viable bacteria(P<0.05)The results showed that FMO,FO and MO significantly increased the contents of soil total nitrogen(STN),soil available phosphorus(SAP),soil available potassium(SAK),soil organic matter(SOM)and soil fulvic acid(SFA)(P<0.05),and decreased the soil p H.The contents of SOM,STN and SFA in soil treated at 10°C,15°C and 20°C changed significantly,SAP and SAK had no significant change in 3 months.The application of FA could reduce the loss of nitrogen in soil and enhance the ability of soil keeping fertilizer The results of water-stable soil aggregates showed that FMO and FO significantly increased the percentage of water-stable soil aggregates > 0.25 mm(P<0.05),and increased the content of soil aggregate structure The results of community structure analysis showed that FMO,FO and MO had difference between soil and CK,and the effect of fertilizer on soil bacterial community was greater than that of temperature.The richness of soil bacteria in FO was higher than that in MO and FMO.FMO and MO could decrease the relative abundance of Actinobacteria,Fusobacteriota,Elusiformis and Dependentiae,and increase the relative abundance of Gemmatimonadetes and Firmicutes.FO application increased the relative abundance of Gemmatimonadetes,Actinobacteria and Actinobacteria,and decreased the relative abundance of Proteobacteria,Bacteroidota and Firmicutes.FA and Bacillus amyloliquefaciens F1 both increased the relative abundance of Pseudomonas in soil and decreased the relative abundance of Massilia.